Bernie Masters is a geologist/zoologist who spent 8 years as a member of the Western Australian Parliament. Married to Carolina since 1976 and living in south west WA, Bernie is involved in many community groups. This blog offers insights into politics, the environment and other issues that annoy or interest him. For something completely different, visit www.fiatechnology.com.au for information about vegetated floating islands - the natural way to improve water quality.

Sunday, July 22, 2018

In March 2015, I posted an article about aspirin and melatonin being two easily accessible drugs that provided useful health benefits. In the case of aspirin, just 75 mg per day was shown to reduce cardiovascular events and the risk of cancer. More recent research - see below - shows that your weight dictates how much aspirin you should take each day to gain these health benefits. If you weigh under 70kg, 75mg of aspirin is sufficient. Over this weight, 325mg or more of aspirin needs to be taken each day to provide increased protection against cardiovascular events and cancer.

Effects
of aspirin on risks of vascular events and cancer according to
bodyweight and dose: analysis of individual patient data from randomised
trials

Summary

Background

A
one-dose-fits-all approach to use of aspirin has yielded only modest
benefits in long-term prevention of cardiovascular events, possibly due
to underdosing in patients of large body size and excess dosing in
patients of small body size, which might also affect other outcomes.

Methods

Using
individual patient data, we analysed the modifying effects of
bodyweight (10 kg bands) and height (10 cm bands) on the effects of low
doses (≤100 mg) and higher doses (300–325 mg or ≥500 mg) of aspirin in
randomised trials of aspirin in primary prevention of cardiovascular
events. We stratified the findings by age, sex, and vascular risk
factors, and validated them in trials of aspirin in secondary prevention
of stroke. Additionally, we assessed whether any weight or height
dependence was evident for the effect of aspirin on 20-year risk of
colorectal cancer or any in-trial cancer.

=0·0072), with benefit seen in people weighing
50–69 kg (hazard ratio [HR] 0·75 [95% CI 0·65–0·85]) but not in those
weighing 70 kg or more (0·95 [0·86–1·04]; 1·09 [0·93–1·29] for vascular
death). Furthermore, the case fatality of a first cardiovascular event
was increased by low-dose aspirin in people weighing 70 kg or more (odds
ratio 1·33 [95% CI 1·08–1·64], p=0·0082). Higher doses of aspirin (≥325
mg) had the opposite interaction with bodyweight (difference pinteraction=0·0013), reducing cardiovascular events only at higher weight (pinteraction=0·017).
Findings were similar in men and women, in people with diabetes, in
trials of aspirin in secondary prevention, and in relation to height (pinteraction=0·0025
for cardiovascular events). Aspirin-mediated reductions in long-term
risk of colorectal cancer were also weight dependent (pinteraction=0·038).
Stratification by body size also revealed harms due to excess dosing:
risk of sudden death was increased by aspirin in people at low weight
for dose (pinteraction=0·0018) and risk of all-cause death
was increased in people weighing less than 50 kg who were receiving
75–100 mg aspirin (HR 1·52 [95% CI 1·04–2·21], p=0·031). In participants
aged 70 years or older, the 3-year risk of cancer was also increased by
aspirin (1·20 [1·03–1·47], p=0·02), particularly in those weighing less
than 70 kg (1·31 [1·07–1·61], p=0·009) and consequently in women (1·44
[1·11–1·87], p=0·0069).

Interpretation

Low
doses of aspirin (75–100 mg) were only effective in preventing vascular
events in patients weighing less than 70 kg, and had no benefit in the
80% of men and nearly 50% of all women weighing 70 kg or more. By
contrast, higher doses of aspirin were only effective in patients
weighing 70 kg or more. Given that aspirin's effects on other outcomes,
including cancer, also showed interactions with body size, a
one-dose-fits-all approach to aspirin is unlikely to be optimal, and a
more tailored strategy is required.